Here is where you can activate or deactivate different types of plugins in order to fulfill your needs. You can find the Plugins section under the System tab.
There is two section to look at for plugins, one is the Activated Plugins and another for Installed Plugins. You can 
or 
any plugins by simply clicking on the icon.
Activated Plugins: here you will see all the plugins that are activated, showing name of the plugin and version
Installed Plugins: will show all the available plugin you can activate or deactivate. You will see the name of the plugin with a brief description